Latent Heat Formula

 

Latent Heat formula

 

Latent heat is the heat required to convert a solid into a liquid or vapor phase, or a liquid into a vapor phase. According to different phase, it has different names like heat of condensation, heat of vaporization etc. The amount of heat energy absorbed or released for a phase change is known as latent heat.

The latent heat formula is given by,

L = Q / M

Where,

Q = amount of heat

M = mass of the substance

 

Example 1

Determine the latent heat of 5kg substance if the amount of heat for a phase change is 300k.cal.

Solution:

Given parameters are,

Q = 300k.cal

M = 5 kg

Formula for latent heat is given by,

L = Q / M

 = 300 / 5

 = 60k.cal/kg

 

Example 2

The heat needed for a phase transfer of 2kg substance is 400k.cal. Determine its latent heat.

Solution:

Given parameters are,

Q = 400k.cal

M = 2 kg

Formula for latent heat is given by,

L = Q / M

 = 400 / 2

 = 200k.cal/kg

Practise This Question

One end of a copper rod of uniform cross-section and of length 3.1 m is kept in contact with ice and the other end with water at 100 C. At what point along it's length should a temperature of 200 C be maintained so that in steady state, the mass of ice melting be equal to that of the steam produced in the same interval  of time. Assume that the whole system is insulated from the surroundings. Latent heat of fusion of ice and vaporisation of water are 80 cal/gm and 540 cal/gm respectively

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